Multiple piston distributive pump with hydraulic system for the synchronized operation of a plurality of working cylinders



July 6, 1965 H BIERI 192,71s

MULTIPLE PISTON DISTRIBUTIVE PUMP WITH HYDRAU SYSTEM FOR THE SYNCHRONIZED OPERATION OF A PLURALITY 0]? WORKING CYLINDERS Filed May 14, 1953 FIELZ :4 21 2s 7 \I 1 I: 3 4 24 5 22 d 25 F x I] I n I w g 7 Ill i, 1|e\\ a 2 United States Patent Oflice 3,l2,7l8 Patented July 6, 1965 3,192,718 MULTHLE PISTON DETRIBUHVTE PUM? Wllii HYDRAULIC SYSTEM FER THE SYNCIRG- NEZED GPERATI UN 013 A PLURALITY 9F WORK- ING CYLINDERS Hans Bieri, Liehefeld, near Bern, Switzerland assignor to H. Bieri dz Sohn, Liehefeld, near Bern, Switzerland, 21 firm Filed May 14, 1953, Ser. No. 289,399 Claims priority, appiication Switzerland, May 14, 1962, 5,774/62 15 (Ilaims. (Cl. 60-52) The invention relates to the synchronized operation of a number of operating units in a hydraulic operating system. This system may, for instance, serve for the lifting, lowering or displacement of very heavy and large goods, especially complete buildings and naturally grown objects.

In conventional hydraulic systems of this kind every unit includes a hydraulic cylinder and piston, and every working cylinder is either fitted with a control valve which allows to manually control the flow of a pumped fluid to or from each cylinder. This method is complicated and the result is an only approximative synchronisation.

Another system includes a multiple chamber synchronizing unit between the pump and the working cylinders, effecting automatically an equal distribution of the pumped fluid among the working cylinders. The synchronisation obtained thereby is perfect, but the number of cylinders to be used is very limited.

The present invention aims at an elimination of these disadvantages and allows the operation of a greater number of working units with perfect synchronisation.

The invention provides a method for synchronized operation of a plurality of operating units in a hydraulic system whereby exactly equal quantities of fluid are withdrawn from the working cylinders by a multiple piston pump and discharged against high pressure.

The multiple piston distributive pump with the hydraulic system for performing this procedure according to the invention is characterized by the following facts:

(a) Provision of a number of working units each comprising one or more pump cylinders directly connected with one or more Working cylinders wherein the piston surfaces of the working cylinders have equal areas and the axial piston displacement in the pump cylinders are equal.

(b) Every pump cylinder is fitted, besides the conventional intake and outlet valves, with both an additional intake and an outlet valve to be used for the return movement of working pistons under load.

The invention will now be described in full details in connection with an embodiment shown in the accompanying drawing.

FIG. 1 is a schematic layout and circuit diagram of a hydraulic system using a multiple piston pump, and

FIG. 2 is a'longitudinal section 'of a pump cylinder unit.

The illustrated hydraulic system uses a multiple piston pump with radial pistons and cylinders and driven by an electric motor 1 through an eccentric 2 schematically illustrated in FIG. 1 as a crank shaft. Of its several radial cylinders 3, only two are shown in FIG. 1, each with its piston 4. According to FIG. 2, the pump piston 4 in the cylinder 3 is pushed to the left by a piston rod 5 once during every revolution of the eccentric 2. By this movement the hydraulic fluid, oil for instance, which completely fills up the pump chamber 6 of the cylinder 3, is discharged through a nonreturn check valve .7 and into a conduit 9 provided with a closure valve 8 and is pressed through a connecting tube 10 into the working chambers 11 of two working cylinders 12 which, in this embodiment are connected as a pair with one pump cylinder chamber 6 of the pump so as to form a operating unit. Each working cylinder 12 is provided with a working piston 13 which is movable in the cylinder.

If the blocking valve 8 is closed, the oil discharged from chamber 6 will pass a nonreturn check valve 14 and enter a discharge conduit 15 from where it is forced through a pressure retaining valve 16 to flow back through conduit 17 into an oil tank 18'.

As soon as eccentric 2 has moved piston 5 to its outermost position, the nonreturn check valves 7 and 14 are closed immediately by spring action (FIG. 2). The further rotation of the eccentric will cause a fall of pressure in the pump chamber 6, which allows a low pressure auxiliary feeder pump 19 (FIG. 1) to deliver oil through a conduit 20 and a nonreturn check valve 21 into pump chamber 6, and to push the piston 4 and plunger 5 to the right, following the slope of the eccentric 2.

This filling stroke, however, may be reduced according to the requirements by adjusting means in the form of a cap nut 22 (FIG. 2) on the fine thread 23 of a guiding bushing 24 which is fixed in the pump cylinder body 3. By this nut, piston 5 is stopped at its shoulder 25 shortly before the end of the eccentric slope. In the outer circumference of the nut there are a number of axial grooves 25 one of which always will be engaged by a ball 28 which is guided in the pump base 27. Thus the piston displacement of every operating unit can be adjusted individually.

Between the closure valve 8 and the coupling 29 (FIG. 1) of the conduit 9 and 19 respectively, there is the branch pipe for a safety valve 30, a pressure gauge 31 and a bypass 32 which is connected through a closure valve 33 and a nonreturn check valve 34 with the cylinder chamber 6.

If valve 8 is closed and valve 33 open and the pistons 13 of the working cylinders are under load, oil is pressed out of working chambers 11 through the conduits 10 and 32 and through the nonreturn check valve 34 into the pump chamber 6 and afterwards during the forward stroke of the piston 4, ejected through valves 7, 14 and 16 back into the discharge tank 18. The pressure retaining valve device 16 is adjusted for a pressure somewhat higher than the maximum pressure occurring in the chambers 11 of the working cylinders.

For every operating unit the oil pressure in the chambers 11 of the working cylinders 12 can be read oil on the pressure gauges 31, which represent the pushing force of every working piston. If one of the working cylinders is overloaded or if a piston has reached the end of its'stroke, the rising oil pressure will open the safety valve 30 and oil will escape into a discharge conduit 35 and through a throttle 36 into the tank 18. The pressure maintained by the throttle 36 immediately actuatesa pressure switch 37 and hereby stops the electromotor 1.

In case of temporary non-use of some pump cylinders a connection 38 attached to coupling 29 serves for the delivery of oil under low pressure only from the pump cylinders 6 through conduits 9 and 38 into conduit 39, which is connected over a pressure maintaining valve 40 with the circuit 293 of a low pressure auxiliary pump 19.

The auxiliary pump 19, the pressure of which is kept constant by a valve 41, not only serves as feeding pump for the piston pump 4, 5, 6 but also allows, over a reversing valve 42, a conduit 43 and a coupling 44, to move the working pistons 13 quickly forward and backward. Previously thereto the conduit 10 has to be switched from coupling 29 to a coupling 44.

The constant low oil pressure maintained by pump 19 in conduits 39 and 47 also acts on the rear of pistons 13. First, the quick withdrawal of these pistons is effectuated hereby and secondly unintentional lowering of the pistons by gravity is made impossible in the case that the cylinders are suspended.

From the above description of the illustrated embodiment follows that in case of non-use, any number of cylinders of this multiple piston pump can be left idle. Every pump cylinder may be connected with only one or with a group of two or more working cylinders to form 21 operating unit. In a contrary case there may also be connected several pump cylinders with only one working cylinder in an operating unit in order to obtain a higher operating speed.

The refined adjustment of the filling stroke of every single pump cylinder permits adjustment of all the cylinders to a perfectly equal delivery, in spite of any tolerances in the machining of the parts. A supplementary increase of the precision of delivery is due to the fact that the multiple piston pump does not suck fiuid from the tank but is fed by an auxiliary pump at a constant pressure. 7

By fitting every pump cylinder with both an additional intake and another outlet valve it is possible under the very'simple control by. two blocking valves, not only to pump oil into the working cylinders but also to withdraw, if desired, exactly equal quantities of oil from them and to pump the oil through a pressure maintaining valve against a constant counter-pressure back into the tank. With this method the synchronized lowering of all the Working cylinders under maximum load can easily be effectuated.

The cylinders of the multiple piston pump may also be arranged in line instead of radially and be driven by a common crankshaft or camshaft.

What I claim is:

1. A hydraulic multiple piston operating system, comprising a plurality of operating units, each unit including at least one working cylinder and a working piston therein forming a working chamber, at least one pump cylinder and a pump piston therein, each pump cylinder having a first inlet means for a working fluid, a second inlet means including a check valve, and an outlet means including a check valve, each operating unit further including conduit means connecting said working chamber with said second inlet means and with said outlet means, respectively; drive means for reciprocating said pump pistons of all said operating units so that said working pistons are operated; a discharge conduit connected to said outlet means; and a check valve in said discharge conduit.

2. A hydraulic multiple piston operating system, comprising a plurality of operating units, each unit including at least one working cylinder and a working piston therein forming a working chamber, at least one pump cylinder and a pump piston therein, each pump cylinder having a first inlet means for a working fluid, a second inlet means, including a check valve, and outlet means including a check valve, each operating unit furtherincluding conduit means connecting'said-working chamher with said second inlet means and with said outlet means, respectively; drive means for reciprocating said pump pistons of all said operating units so that said working pistons are operated; a discharge tank; an'auX- iliary pump having discharge means connected to said first inlet means and an inlet connected to said discharge tank; a discharge conduit connecting said outlet means with said discharge tank; and a check valve in said discharge conduit.

3. A hydraulic multiple piston operating system, comprising a plurality of operating units, each unit including at least one working cylinder and a working piston therein forming a working chamber, at least one pump cylinder and a pump piston therein, each pump cylinder having a first inlet means for a working fluid and including a check valve, 21 second inlet means including a check valve, and outlet means including a check valve, each operating unit further including conduit means connected with said working chamber, and first and second closure valves connecting said conduit means with said second inlet means and with said outlet means, respectively; drive means for reciprocating said pump pistons of all said operating units so that said Working pistons are operated when said second closure valves are open and said first closure valves are closed during a reciprocating stroke in one direction, and so that fluid is returned from said working chamber to said pump cylinder when said first closure valves are opened and said second closure valves are closed during an opposite reciprocating stroke; a discharge tank; an auxiliary pump having discharge means connected to said first inlet means and an inlet connected to said discharge tank; a discharge conduit connecting said second closure valve and said outlet means with said discharge tank; and a check valve in said discharge conduit.

4. A hydraulic multiple piston operating system, comprising a plurality of operating units, each unit including at least one working cylinder and a piston therein forming a working chamber, at least one pump cylinder and a piston therein, each pump cylinder having a first inlet means for a Working fluid, and including a check valve, a second inlet means including a check valve, and outlet means including a check valve, each operating unit further including conduit means connected with said working chamber, and first and second closure valves connecting said conduit means with said second inlet means and with said outlet means, respectively; means for supplying a working fiuid to said first inlet means of said pump cylinders of all said operating units; and drive means for reciprocating said pump pistons of all said working units so that said working pistons are operated when said second closure valves are open during a reciprocating stroke in one direction, and so that fluid is returned from said working chamber to said pump cylinder when said first closure valve is opened and said second closure valve is closed during an opposite reciprocating stroke.

5. A hydraulic multiple piston operating system, comprising a plurality of operating units, each unit including at least one working cylinder and a piston therein forming a working chamber, at least one pump cylinder and a piston therein forming a pump chamber, each pump cylinder having a first inlet means for a Working fluid, and including a check valve, a second inlet means including a check valve, and outlet means including a check valve, each operating unit further including conduit means connected with said working chamber, and first and second closure valves connecting said conduit means with said second inlet means and with said outlet means, respectively; adjusting means on said pump cylinder for adjusting the stroke of said piston therein and thereby the volume of said pump chamber independently of the other operating units; means for supplying a work ing fluid to said first inlet means of said pump cylinders of all said working units; and drive means for reciprocating said pump pistons of all said operating unitsso that said working pistons are operated when said second closure valves are open during a reciprocating stroke in one direction, and so that fluid is returned from said working chamber to said pump cylinder when said first closure valve is opened and said second closure valve is closed during an opposite reciprocating stroke.

6. A hydraulic multiple piston operating system, comprising a plurality of operating units, each unit including at least one working cylinder and a working piston therein forming a working chamber, at least one pump cylinder and a pump piston therein forming a pump chamber, each pump cylinder having a first inlet means for a working fluid, a second inlet means, and an outlet means, each operating unit further including conduit means connecting said working chamber with said second inlet means and with said outlet means respectively; adjusting means on said pump cylinder for adjusting the stroke of said piston therein and thereby the volume of said pump chamber independently of the other operating units; drive means for reciprocating said pump pistons of all said operating units so that said working pistons are operated; a discharge tank; a discharge conduit connecting said outlet means with said discharge tank; and a check valve in said discharge conduit.

7. A hydraulic multiple piston operating system, comprising a plurality of operating units, each unit including at least one working cylinder and a working piston therein forming a working chamber, at least one pump cylinder and a pump piston therein forming a pump chamber, each pump cylinder having a first inlet means for a working fiuid and including a check valve, a second inlet means including a check valve, and an outlet means including a check valve, each operating unit further including conduit means connected with said Working chamber, and first and second closure valves connecting said conduit means with said second inlet means and with said outlet means, respectively; adjusting means on said pump cylinder for adjusting the stroke of said piston therein and thereby the volume of said pump chamber independently of the other operating units; drive means for reciprocating said pump pistons of all said operating units so that said working pistons are operated when said second closure valves are open and said first closure valves are closed during a reciprocating stroke in one direction, and so that fluid is returned from said working chamber to said pump cylinder when said first closure valves are opened and said second closure valves are closed during an opposite reciprocating stroke; a discharge tank; an auxiliary pump having discharge means connected to said first inlet means and an inlet connected to said discharge tank; a discharge conduit connecting said second closure valve and Said outlet means with said discharge tank, a check valve in said discharge conduit, and a pressure-maintaining valve device in said discharge conduit.

8-. A system as set forth in claim 5 wherein each adjusting means includes a cap nut mounted on the respective pump cylinder, and arresting means for arresting each cap nut in a plurality of turned adjusting positions.

9. A system as set forth in claim 8 wherein said arresting means include axial recesses on each cap nut, and a spring-loaded ball cooperating with said recesses.

it). A system as set forth in claim 1 and including a second Working cylinder and piston having a working chamber connected with said conduit means.

11. A system as set forth in claim 1 wherein said drive means includes a crank shaft, and wherein said pump pistons of two working units are reciprocated in opposite directions.

12. A system as set forth in claim 1 including a safety valve in said conduit means, a pressure conduit connecting said safety valve with said discharge tank, and pressure responsive means in said pressure conduit actuated by over pressure and connected to said drive means for stopping the same when actuated.

13. A hydraulic multiple piston operating system, comprising a plurality of operating units, each unit including at least one working cylinder and a working piston therein forming a working chamber, at least one pump cylinder and a pump piston therein, each pump cylinder having a first inlet means for a working fluid, a second inlet means, and an outlet means, each operating unit further including conduit means connecting said working chamber with said second inlet means and with said outlet means, respectively; drive means for reciprocating said pump pistons of all said operating units so that said working pistons are operated; a discharge tank; a discharge conduit connecting said outlet means with said discharge tank, a check valve in said discharge conduit, and a pressure maintaining valve device in said conduit.

14. A hydraulic multiple piston operating system, comprising a plurality of operating units, each unit including at least one working cylinder and a piston therein forming a working chamber, at least one pump cylinder and a piston therein, each pump cylinder having a first inlet means for a working fluid, and including a check valve, a second inlet means including a check valve, and an outlet means including a check valve, each operating unit further including conduit means connecting said working chamber with said second inlet means and with said outlet means, respectively; means for supplying a working fluid to said first inlet means of said pump cylinders of all said operating units; drive means for re ciprocating said pump pistons of all said working units; a discharge conduit connected to said outlet means; a check valve in said discharge conduit; and a pressuremaintaining device in said discharge conduit.

15. A system as set forth in claim 14 wherein said working piston and said pump piston have strokes of equal length and transverse pressure faces of equal areas.

References Cited by the Examiner UNITED STATES PATENTS 1,460,586 7/23 Howse 52 2,597,050 5/52 Audemar 6051 JULIUS E. WEST, Primary Examiner.

EDGAR W. GEOGHEGAN, Examiner. 

1. A HYDRAULIC MULTIPLE PISTON OPERATING SYSTEM, COMPRISING A PLURALITY OF OPERATING UNITS, EACH UNIT INCLUDING AT LEAST ONE WORKING CYLINDER AND A WORKING PISTON THEREIN FORMING A WORKING CHAMBER, AT LEAST ONE PUMP CYLINDER AND A PUMP PISTON THEREIN, EACH PUMP CYLINDER HAVING A FIRST INLET MEANS FOR A WORKING FLUID, A SECOND INLET MEANS INCLUDING A CHECK VALVE, AND AN OUTLET MEANS INCLUDING A CHECK VALVE, EACH OPERATING UNIT FURTHER INCLUDING CONDUIT MEANS CONNECTING SAID WORKING CHAMBER WITH SAID SECOND INLET MEANS AND WITH SAID OUTLET MEANS, RESPECTIVELY; DRIVE MEANS FOR RECIPROCATING SAID PUMP PISTONS OF ALL SAID OPERATING UNITS SO THAT SAID WORKING PISTONS ARE OPERATED; A DISCHARGE CONDUIT CONNECTED TO SAID OUTLET MEANS; AND A CHECK VALVE IN SAID DISCHARGE CONDUIT. 